Flexible duct hoses consist of fire-resistant PVC material with spiral steel wire as reinforcement. The exterior is made of high-density polyester fabric with black PVC strips. These hoses can endure high temperature and are oil, acid, alkali and abrasion resistant. Due to its highly compressible and flexible nature, they are convenient for storage and easy to transport. They are used for ventilation of exhaust air, dust extractions and fresh air supply. They are widely used in airports, tunnels, basements, etc.